Heat shrink films and articles encapsulated therein

Abstract

The present invention relates to a heat shrink film for encapsulating articles comprising a core layer having an upper surface and a lower surface, a first skin layer on the upper surface of the core layer, and a second skin layer underlying the lower surface of the core layer, wherein the core layer comprises a blend of (i) at least one polyterpene and (ii) a syndiotactic polypropylene or a cyclic olefin copolymer, wherein the ultimate shrinkage of the film is at least 25% at 135° C.

1 . A multilayered heat shrink film for encapsulating articles comprising:
 a core layer having an upper surface and a lower surface;   a first skin layer on the upper surface of the core layer; and   a second skin layer underlying the lower surface of the core layer;   wherein the core layer comprises a blend of (i) at least one polyterpene; (ii) a syndiotactic polypropylene or a cyclic olefin copolymer; and (iii) a nucleated homopolymer or copolymer of polypropylene, wherein the ultimate shrinkage of the film is at least 25% at 135° C. as measured by ASTM D1204.   
   
   
       2 . The film of  claim 1  wherein the polyterpene comprises a hydrogenated polyterpene. 
   
   
       3 . The film of  claim 1  wherein the core layer further comprises polyisobutylene. 
   
   
       4 . The film of  claim 1  wherein the core layer further comprises one or more thermoplastic polymers. 
   
   
       5 . The film of  claim 4  wherein the core layer further comprises one or more of (i) a copolymer of polypropylene and another alpha olefin, (ii) a copolymer of polyethylene and another alpha olefin, (iii) a polyethylene, and (iv) combinations thereof. 
   
   
       6 . The film of  claim 1  wherein the first and second skin layers comprise one or more polyolefins. 
   
   
       7 . The film of  claim 6  wherein the one or more polyolefins comprise one or more of a homopolymer of butylene, a copolymer of polypropylene and another alpha olefin, a copolymer of polyethylene and another alpha olefin, a polyethylene, a functionalized polyethylene, and combinations thereof. 
   
   
       8 . The film of  claim 7  wherein the first and second skin layers further comprise a hydrogenated polyterpene. 
   
   
       9 . The film of  claim 7  wherein at least one skin layer further comprises a thermoplastic material of a copolymer of an ethylene-unsaturated carboxylic acid or anhydride, an ionomer derived from sodium, lithium, or zinc and ethylene/unsaturated carboxylic acid or anhydride copolymers or combinations thereof. 
   
   
       10 . The film of  claim 1  wherein the shrink tension of the film is less than 3135 kPa at 135° C., as measured by ASTM Method D2838. 
   
   
       11 . A heat shrink film for encapsulating articles comprising a blend of:
 (i) a nucleated homopolymer of polypropylene;   (ii) at least one polyterpene; and   (iii) a syndiotactic polypropylene or a cyclic olefin copolymer wherein the ultimate shrinkage of the film is at least 25% at 135° C. as measured by ASTM Method D1204.   
   
   
       12 . The film of  claim 11  wherein the polyterpene is a hydrogenated polyterpene. 
   
   
       13 . The film of  claim 11  wherein the film further comprises one or more thermoplastic polymers. 
   
   
       14 . The film of  claim 11  wherein the film is uniaxially oriented in the machine direction only. 
   
   
       15 . The film of  claim 11  wherein the shrink tension of the film is less than 3135 kPa at 135° C. as measured by ASTM D2838. 
   
   
       16 . The film of  claim 11  wherein the film is a monolayer film. 
   
   
       17 . The film of  claim 11  wherein the film further comprises polyisobutylene. 
   
   
       18 . The film of  claim 11  wherein the film comprises a multilayer film.